nm is a Unix command used to dump the symbol table and their attributes from a binary executable file (including libraries, compiled object modules, shared-object files, and standalone executables).

The output from nm distinguishes between various symbol types. For example, it differentiates between a function that is supplied by an object module and a function that is required by it. nm is used as an aid for debugging, to help resolve problems arising from name conflicts and C++ name mangling, and to validate other parts of the toolchain.

This command is shipped with a number of later versions of Unix and similar operating systems including Plan 9. The GNU Project ships an implementation of nm as part of the GNU Binutils package.

The etymology is that in the old Version 7 Unix, nm's manpage used the term name list instead of symbol table.

If the previous code is compiled with the gcc C compiler, the output of the nm command is the following:

When the C++ compiler is used, the output differs:

The differences between the outputs also show an example of solving the name mangling problem by using extern "C" in C++ code.